Ammoxydation has long been industrially practiced. Many improvements have been made for ammoxydation from the standpoint of catalyst. However, few proposals have been made for the structure of an apparatus (sparger) for supplying and spraying the starting material. It is disclosed in U.S. Pat. No. 4,801,731 (JP-A-2-258 (The term "JP-A" as used herein means an "unexamined published Japanese patent application")). All these proposals feature the disposition of an oxygen gas exit orifice and a propylene/ammonia exit orifice opposed to each other.
British Patent 1,265,770 describes the provision of a sparger disposed in the form of a ring on the peripheral portion of the reactor. However, the object of this arrangement is to prevent the accumulation of a catalyst on the peripheral portion of the reactor. No reference is made to reactivity.
Few proposals have been made for the structure of dispersing plate or dispersing pipe. In particular, the pressure loss in a dispersing plate or dispersing pipe is disclosed in Daizo Kunii, Fluidization Engineering, Octave Levenspiel, John Wiley & Sons. Inc., page 87 (1969). In this reference, 0.1 times the pressure loss in a fluidized bed is recommended as the pressure loss required for fluidized gas dispersing pipe or dispersing plate. However, it was found that if gases are supplied through two systems in an industrial scale apparatus having a column diameter of not less than 3 m, the distribution of the supplied gas concentration is localized under the foregoing conditions, resulting in the reduction of the yield of the objective unsaturated nitrile.